import pywikibot
site = pywikibot.Site('en', 'wikipedia')
cat = pywikibot.Category(site, "Category:French writers")
cats = cat.subcategories(total=3)
for c in enumerate(cats): print c
cats1 = cat.subcategories()
for c in enumerate(cats1): print cgives:
(0, Category(Category:French Guianan writers))
(1, Category(Category:French Polynesian writers))
(2, Category(Category:Guadeloupean writers))
(0, Category(Category:French Guianan writers))
(1, Category(Category:French Polynesian writers))
(2, Category(Category:Guadeloupean writers))
while the category has 26 subcategories instead.